This invention relates to a dispensing apparatus and, more particularly, to such an apparatus for dispensing a liquid product from a sealed container.
Liquefied fluorocarbon gases, such as those sold under trade name of Freon, have been used as propellants to discharge a liquid product from a container such as a can, a bottle, a beer keg, a soft drink dispensing machine, or the like. Liquefied fluorocarbon gas exists in the container as a liquid and often can be mixed with the product to be dispensed. Since the vapor pressure of the liquefied fluorocarbon gas exceeds atmospheric pressure at a temperature in which the product is discharged, and since the pressure in the container is substantially equal to the vapor pressure of the liquefied fluorocarbon gas and is independent of the volume of the free space of the container, the pressure of the container will be virtually constant throughout the discharge life of the system as long as the liquefied fluorocarbon gas is present in the container. However, fluorocarbons have adverse effects on the atmosphere and have even been banned in some jurisdictions.
Although other systems have been used which do not require the use of fluorocarbons, their vapor pressure is such that the product cannot be dispensed at a constant pressure through the life of the product. Therefore some type of manual actuation is required prior to dispensing which is costly and inconvenient.